computer virus

Definitions

from The American Heritage® Dictionary of the English Language, 4th Edition

n. A computer program that is designed to replicate itself by copying itself into the other programs stored in a computer. It may be benign or have a negative effect, such as causing a program to operate incorrectly or corrupting a computer's memory.

from Wiktionary, Creative Commons Attribution/Share-Alike License

n. A program which can covertly transmit itself between computers via networks (especially the Internet) or removable storage such as CDs, USB drives, floppy disks, etc., often causing damage to systems and data.